CN103499438B - Based on the material Adaptability Evaluation Method of residual life - Google Patents

Abstract

The invention discloses a kind of material Adaptability Evaluation Method based on residual life, the first step: the residual life of predict device; Second step: the residual life of prediction was compared with the life-span of expectation; 3rd step: residual life is less than the life-span that user expects, reports to the police, and analyzes corrosion rate further; 4th step: corrosion rate exceedes value of setting up defences, and proposed materials is upgraded.For the deficiency of present material environmental suitability evaluation method, proposing and residual life impact introduced in existing material environment Adaptability Evaluation Method, is to existing methodical important supplement and perfect.It is also proposed a kind of method for predicting residual useful life of practicality, for the material environment Adaptability Evaluation realizing the life-cycle is laid a good foundation.

Description

Based on the material Adaptability Evaluation Method of residual life

Technical field

The invention belongs to landification equipment safety assessment technique field, be specifically related to predicting residual useful life and the adaptability for materials evaluation of petrochemical equipment.

Background technology

Oil variety day by day variation causes the sulphur content cloth in oil product and the continuous change of acid distribution, and petrochemical equipment because of material and incompatible equipment corrosion, erosion, the coking situation brought of its environment of being on active service day by day serious, the principal risk that becoming affect petrochemical equipment even running is originated.Therefore, petrochemical equipment existing military service material and current equipment refine crude oil adaptability problem just become very important, if material can not meet current Service Environment requirement, so will carry out necessary upgrading to existing material, so not only be conducive to the safety of support equipment, and can effectively prevent unplanned property from stopping work, reduce costs, extension device serviceable life.

Current material upgrading principle is mainly evaluated its adaptability for materials problem by the corrosion mechanism to petrochemical equipment internal corrosion media variations situation and corresponding bearing device after crude oil in poor quality, corrosion rate situation of change.By exceeding the material of value of setting up defences to corrosion rate, provide the suggestion of upgrading, the corrosion of the equipment in whole device can be made to consume after material upgrading and substantially be in same level line, thus eliminate the weak link in device.

Although it is the adaptive key character of reflection material environment that corrosion rate exceeds standard, the residual life of equipment more can reflect the possibility of equipment failure, therefore, is another key character of evaluating material environmental suitability.But current material environment Adaptability Evaluation Method does not all consider the residual life impact of equipment.

Summary of the invention

Residual life is a reflection material environment adaptive key character, and residual life impact is introduced in existing material environment Adaptability Evaluation Method by the present invention, is to existing methodical important supplement and perfect.

The process of put forward the methods of the present invention is as follows: on the basis of damage mechanism analysis, according to evaluation, the rating scale of e-quipment and pipe design standards, damage, formulates the residual life assessment method based on uniform corrosion and local corrosion.If residual life is less than the life-span that user expects, report to the police, analyze corrosion rate further and whether exceed value of setting up defences, if exceeded standard, judge that material can not meet environmental suitability, material upgrading is carried out in suggestion, otherwise, only provide the prompting of residual life deficiency.

Pipeline residual Life Calculation subelement carries out, i.e. straight tube, elbow, threeway, reduced pipe; Container residual Life Calculation divides tower, spherical tank, horizontal vessel, vertical vessel.(as GB/T20801.3, GB/T19624, JB4732, GB50316) is calculated by concerned countries, industry standard, undertaken by elastic failure criterion and plastic failure criterion respectively, as long as meet one of them criterion namely to think and do not lose efficacy, safe handling can be continued.

Whether predicting residual useful life process is as follows: lost efficacy by current actual measurement wall thickness calculate, if lost efficacy, wall thickness was subtracted year corrosion rate and calculate as new wall thickness (namely a year after calculated wall thickness) and whether lost efficacy, so repeatedly, until lost efficacy, calculated and terminated.There is last computation wall thickness when losing efficacy and safe wall thickness, cycle index and the residual life time limit.Above-mentioned computation process is realized by software systems, avoids artificial complicated calculations.

The invention has the beneficial effects as follows: for the deficiency of present material environmental suitability evaluation method, propose and residual life impact introduced in existing material environment Adaptability Evaluation Method, is to existing methodical important supplement and perfect.It is also proposed a kind of method for predicting residual useful life of practicality, for the material environment Adaptability Evaluation realizing the life-cycle is laid a good foundation.

Embodiment

To be specifically described implementation process of the present invention at three catalytic unit P-206 pipeline straight lengths of certain petroleum chemical enterprise and D-102 spherical tank uniform corrosion.By manually to calculate or software systems realize predicting residual useful life process.

Embodiment one

Based on the material Adaptability Evaluation Method of the residual life of pipeline straight tube uniform corrosion

Step 1: obtaining corrosion rate according to corrosion monitoring (spot thickness measurement or on-line corrosion monitoring) or corrosion analysis is 0.5mm/.

Step 2: select tubular type to be " straight tube ", elastic failure criterion presses GB/T20801.3-2006 " pressure pipeline specification industrial pipeline the 3rd part: project navigator " criterion calculation, and plastic failure criterion presses JB4732-95 " Steel Pressure Vessels analysis and designation standard " criterion calculation.

Step 3: input calculating parameter, the 4 years serviceable life of expectation of this straight tube.

By straight tube correlation parameter as table 1, bring in the standard in step 2, calculate, calculation procedure is as follows:

Elastic failure criterion: $\frac{p(D_o-2\mathrm{Yt})}{2t{\mathrm{\Φ}}_L}\≤S---\left(1\right)$

Plastic failure criterion, circumference stress is checked: $p\≤\frac{P_{L0}}{1.8}---\left(2\right)$

Plastic failure criterion, axial stress is checked: ${\left(\frac{p}{P_{\mathrm{Lo}}}\right)}^2+{\left(\frac{M_A}{M_{\mathrm{Lo}}}\right)}^2\≤0.44---\left(3\right)$

Wherein:

P---on-stream pressure, MPa;

D _o---pipe fitting overall diameter, mm;

T---pipe fitting calculated wall thickness, mm;

S---tube material permissible stress under operating temperature, MPa;

Φ _l---pipe fitting longitudinal seam welding coefficient: weld pipe 100%RT detects or solid drawn tube gets 1.0, and weld pipe does not detect or inspects by random samples gets 0.80;

Φ _c---pipe fitting girth joint welding coefficient: 100%RT detects and then gets 1.0, does not detect or inspects by random samples, getting 0.80

CA---corrosion allowance, mm, if without these data, then by project engineering practice, stainless steel gets 0, and other steel get 1.6

T _n---pipe fitting nominal thickness, mm;

Y---design factor, dimensionless, wherein D _i=D _o-2t;

---flow stress, Mpa, for alloy steel for mild carbon steel wherein Φ=min (Φ _l, Φ _c);

P _l0---pressure in zero defect pipeline plastic limit, MPa, computing formula:

wherein R _o=D _o/ 2, R _i=R _o-t=D _o/ 2-t;

M _l0---the plastic limit bending moment under Based on Pure Bending Moment, Nmm, computing formula:

wherein R _o=D _o/ 2, R _i=R _o-t=D _o/ 2-t;

M _a---long-time load moment of flexure, Nmm, computing formula:

$M_A=S[{\mathrm{\Φ}}_C-{\mathrm{\Φ}}_L\·\frac{D_o\×\max (0.9t_n-\mathrm{CA}-0.5,t_X)}{2[D_o-2Y\·\max (0.9t_n-\mathrm{CA}-0.5,t_X)]\×(0.9t_n-\mathrm{CA})}]\×\frac{\mathrm{\π}{D}_o^3}{32}(1-{\mathrm{\α}}^4)$

Wherein α=D _i/ D _o; D _i=D _o-2t; t _x---the shaping minimum permission thickness of pipeline, carbon steel and low alloy steel are 3mm, and high-alloy steel (as stainless steel) is 2mm.

Whether lost efficacy by current wall thickness calculate, and if result of calculation does not meet formula (1), also do not meet formula (2) or (3) simultaneously, namely think and there occurs inefficacy.

If result of calculation meets formula (1), then think and lost efficacy.

If result of calculation meets formula (2) and (3), then think and lost efficacy.

If lost efficacy, then carry out step 4.

Table 1 calculates input calculating parameter when whether losing efficacy

Step 4: start prediction and calculation, deducts average annual etching extent (i.e. year corrosion rate) by actual measurement wall thickness, repeat the 3rd step, determine whether to lose efficacy, until lost efficacy, and calculating end, cycle index and the residual life time limit.

The present embodiment obtains residual life 2.5 years, is less than and expects 4 years serviceable life, carry out upgrade of material warning;

Step 5: corrosion rate is drawn by step 1.Due in the present embodiment, corrosion rate 0.5mm/ exceedes user preset value (this example gets 0.35mm/) and residual life is less than and expects serviceable life, suggestion customer upgrade material.

Embodiment two

Based on the material Adaptability Evaluation Method of the residual life of spherical tank uniform corrosion

Step 1: obtaining corrosion rate according to corrosion monitoring (spot thickness measurement or on-line corrosion monitoring) or corrosion analysis is 0.3mm/.

Step 2: select Container Type to be " spherical tank ", elastic failure criterion presses GB12337-1998 " steel-made ball storage tank " criterion calculation, plastic failure criterion presses GB19624-2004 " with containing defect Safty Evaluation of Pressure Vessels " criterion calculation.

Step 3: input calculating parameter as table 2, the 4 years serviceable life of expectation of this spherical tank.

By the correlation parameter of spherical tank, bring in the standard in step 2, calculate:

Elastic failure criterion: $\frac{p(D_o-t)}{4\mathrm{t\Φ}}\≤S---\left(3\right)$

Plastic failure criterion: $p\≤\frac{P_{L0}}{1.8}---\left(4\right)$

Wherein:

P---on-stream pressure, MPa;

D _o---spherical tank (shell) overall diameter, mm;

T---spherical shell calculated wall thickness, mm;

S---material permissible stress under operating temperature, Mpa;

Φ---double-welded butt joint and be equivalent to the complete penetraction and fusion in welding open joint of welding by both sides: 100% Non-Destructive Testing is got 1.00 local Non-Destructive Testings and got 0.85;

---flow stress, Mpa, for alloy steel for mild carbon steel ${\stackrel{\‾}{\mathrm{\σ}}}^{\′}=0.5\mathrm{\Φ}({\mathrm{\σ}}_s+{\mathrm{\σ}}_b);$

P _l0---pressure in zero defect cylindrical shell plastic limit, MPa, computing formula:

wherein R _o=D _o/ 2, R _i=R _o-t=D _o/ 2-t

Whether lost efficacy by current wall thickness calculate, and if result of calculation does not meet formula (3), also do not meet formula (4), namely think and there occurs inefficacy.

If result of calculation meets formula (3), then think and lost efficacy.

If result of calculation meets formula (4), then think and lost efficacy.

Lost efficacy, then carry out step 4.

Step 4: start prediction and calculation, actual measurement wall thickness is deducted average annual etching extent, repeats the 3rd step, determines whether to lose efficacy, until lost efficacy, calculated and terminated, cycle index and the residual life time limit, this example obtains residual life 3 years, is less than and expects 4 years serviceable life, carry out upgrade of material warning.

Step 5: corrosion rate is drawn by step 1.Because the corrosion rate in the present embodiment is that 0.3mm/ exceedes user preset value (this example gets 0.25mm/) and residual life is less than and expects serviceable life, suggestion customer upgrade material.

Table 2 inputs calculating parameter

Claims (3)

1., based on the material Adaptability Evaluation Method of residual life, it is characterized in that:

The first step: the residual life of predict device;

Second step: the residual life of prediction was compared with the life-span of expectation;

3rd step: residual life is less than the life-span that user expects, reports to the police, and analyzes corrosion rate further;

4th step: corrosion rate exceedes value of setting up defences, and proposed materials is upgraded;

The forecasting process of residual life is as follows:

The first step: the wall thickness of measuring equipment;

Second step: whether lost efficacy by current actual measurement wall thickness calculate, above-mentioned calculating adopts national standard, industry standard, calculates respectively by elastic failure criterion and plastic failure criterion;

3rd step: the inefficacy carried out according to elastic failure criterion and plastic failure criterion calculates, as long as one of them lost efficacy, then judges not lose efficacy; Do not lose efficacy, carried out the 4th step;

4th step: actual measurement wall thickness is deducted average annual etching extent, repeats second step, the 3rd step, determines whether to lose efficacy;

5th step: repeat the 4th step, until lost efficacy, calculated and terminated, cycle index and the residual life time limit.

2. the material Adaptability Evaluation Method based on residual life according to claim 1, is characterized in that: pipeline residual Life Calculation is by element: straight tube, elbow, threeway, reduced pipe calculate respectively.

3. the material Adaptability Evaluation Method based on residual life according to claim 1, is characterized in that: container residual Life Calculation calculates respectively by tower, spherical tank, horizontal vessel, vertical vessel.